Wireless local area networks (WLANs), such as those defined by the IEEE 802.11 standard, are becoming more common for enterprises such as businesses, universities, and other organizations in order to provide effective wireless coverage to a defined area. The WLANs function by having a large number of access points physically distributed throughout the coverage area and connected to a network. The WLAN may be further connected to other networks, including for example the Internet or the public switched telephone network. The WLAN allows users to freely move about an enterprise coverage area and use a mobile wireless device to engage in services, including real-time packet-based services such as VoIP, as the device connection is switched from access point to access point.
Enterprises are recognizing the advantages of wireless VoIP as a means of providing ready and secure access to persons within the enterprise coverage area while at the same time reducing the toll costs associated with traditional wide area network (WAN) cellular phones operated by third party providers.
WLANs will often have overlapping coverage areas with traditional cellular networks. Accordingly, there is a desire for a communications system in which voice calls can be handed-off between a cellular network and a WLAN with minimal effect on the quality of the voice call during handoff.
Like reference numerals are used throughout the Figures to denote similar elements and features.